Protein kinases play a critical role in the control of cell growth and differentiation and are key mediators of cellular signals leading to the production of growth factors and cytokines. See, for example, Schlessinger and Ullrich, Neuron 1992, 9, 383. A partial non-limiting list of such kinases includes abl, ARaf, ATK, ATM, bcr-abl, Blk, BRaf, Brk, Btk, CDK1, CDK2, CDK3, CDK4, CDK5, CDK6, CDK7, COK8, CDK9, cfms, c-fms, c-kit, c-met, cRaf1, CSF1R, CSK, c-src, EGFR, ErbB2, ErbB3, ErbB4, ERK, ERK1, ERK2, Fak, fes, FGFR1, FGFR2, FGFR3, FGFR4, FGFR5, Fgr, FLK-4, Fps, Frk, Fyn, GSK, gsk3a, gsk3b, Hck, IGF-1R, IKK, IKK1, IKK2, IKK3, INS-R, Integrin-linkedkinase, Jak, JAK1, JAK2, JAK3, JNK, JNK, Lck, Lyn, MEK, MEK1, MEK2, p38, PDGFR, PIK, PKB1, PKB2, PKB3, PKC, PKCα, PKC⊖, PKCδ, PKCε, PKCγ, PKCλ, PKCμ, PKCζ, PLK1, Polo-like kinase, PYK2, tie1, tie2, TrkA, TrkB, TrkC, UL13, UL97, VEGF-R1, VEGF-R2, Yes and Zap70. Protein kinases have been implicated as targets in central nervous system disorders such as Alzheimer's (Mandelkow, E. M. et al. FEBS Lett. 1992, 314, 315. Sengupta, A. et al. Mol. Cell. Biochem. 1997, 167,99), pain sensation (Yashpal, K. J. Neurosci. 1995, 15, 3263–72), inflammatory disorders such as arthritis (Badger, J. Phanm. Exp. Ther. 1996, 279, 1453), psoriasis (Dvir, et al, J. Cell Biol. 1991, 113, 857), and chronic obstructive pulmononary disease, bone diseases such as osteoporosis (Tanaka et al, Nature, 1996, 383, 528), cancer (Hunter and Pines, Cell 1994, 79, 573), atherosclerosis (Hajjar and Pomerantz, FASEB J. 1992, 6, 2933), thrombosis (Salari, FEBS 1990, 263, 104), metabolic disorders such as diabetes (Borthwick, A. C. et al. Biochem. Biophys. Res. Commun. 1995, 210, 738), blood vessel proliferative disorders such as angiogenesis (Strawn et al Cancer Res. 1996, 56, 3540; Jackson et al J. Pharm. Exp. Ther. 1998, 284, 687), restenosis (Buchdunger et al, Proc, Nat Acad. Sci USA 1991, 92, 2258), autoimmune diseases and transplant rejection (Bolen and Brugge, Ann. Rev. Immunol. 1997, 15, 371) and infectious diseases such as viral (Littler, E.Nature 1992, 358,160), and fungal infections (Lum, R. T. PCT. lnt. Appl., WO 9805335 A1 980212).
The VEGF-R2 kinase is a receptor tyrosine kinase found in endothelial cells and is involved in angiogenesis—the growth and proliferation of blood vessels from existing capillaries. Angiogenesis plays an important role in development, homeostasis, wound healing, the female reproductive cycle, and in pathological conditions such as rheumatoid arthritis, diabetic retinopathy, macular degeneration, psoriasis and cancer. VEGF-R2 kinase transmits the signal initiated by binding of Vascular Endothelial Growth Factor (VEGF) to the extracellular receptor. Signal transmission to the cell interior is accomplished via tyrosine phosphorylation by VEGF-R2, which prompts proliferation of endothelial cells and the release of cytokines and other cellular processes that result in the growth of new blood vessels. Angiogenesis is critical to the growth of cancerous tumors. Solid tumors will not grow beyond 1–2 mm in size without the support of additional vascularization. Most tumor types, if not all, secrete VEGF in order to stimulate angiogenesis. Inhibition of VEGF-R2 kinase would therefore interrupt a critical process involved in tumor growth and metastasis as well as other pathologic angiogenic conditions.